// ==UserScript==
// @name           Down Dou's Music
// @author         chenze - surfchen.org
// @namespace      http://www.liulanqi.org/Firefox/DownDouMusic
// @include        http://www.douban.com/artist/*
// ==/UserScript==
//


/*
 *
 * base64解码来自: http://www.webtoolkit.info/javascript-base64.html
 *
 * */
var Base64 = {
 
	// private property
	_keyStr : "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",
 
	// public method for decoding
	decode : function (input) {
		var output = "";
		var chr1, chr2, chr3;
		var enc1, enc2, enc3, enc4;
		var i = 0;
 
		input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");
 
		while (i < input.length) {
 
			enc1 = this._keyStr.indexOf(input.charAt(i++));
			enc2 = this._keyStr.indexOf(input.charAt(i++));
			enc3 = this._keyStr.indexOf(input.charAt(i++));
			enc4 = this._keyStr.indexOf(input.charAt(i++));
 
			chr1 = (enc1 << 2) | (enc2 >> 4);
			chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
			chr3 = ((enc3 & 3) << 6) | enc4;
 
			output = output + String.fromCharCode(chr1);
 
			if (enc3 != 64) {
				output = output + String.fromCharCode(chr2);
			}
			if (enc4 != 64) {
				output = output + String.fromCharCode(chr3);
			}
 
		}
 
		output = Base64._utf8_decode(output);
 
		return output;
 
	},
	 
	// private method for UTF-8 decoding
	_utf8_decode : function (utftext) {
		var string = "";
		var i = 0;
		var c = c1 = c2 = 0;
 
		while ( i < utftext.length ) {
 
			c = utftext.charCodeAt(i);
 
			if (c < 128) {
				string += String.fromCharCode(c);
				i++;
			}
			else if((c > 191) && (c < 224)) {
				c2 = utftext.charCodeAt(i+1);
				string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
				i += 2;
			}
			else {
				c2 = utftext.charCodeAt(i+1);
				c3 = utftext.charCodeAt(i+2);
				string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
				i += 3;
			}
 
		}
 
		return string;
	}
 
}

function downDouMusic() {
    var sdata;
    var w;
    if ((typeof unsafeWindow)!='undefined') {
        w=unsafeWindow;
    } else if ((typeof window)!='undefined') {
        w=window;
    } else {
        return;
    }
    if ((typeof w.sdata)=='undefined') {
        return
    }
    sdata=w.sdata;
    var songlist_e=document.getElementById('songlist');
    if (!songlist_e) {
        return;
    }
    
    var count;

    var tds=songlist_e.getElementsByTagName('td');
    count=tds.length;
    for (var i=0;i<count;++i) {
        if (tds.item(i).className=='j a_down_title') {
            tds.item(i).style.visibility='visible';//把"下载"两个字显示出来
            break;
        }
    }

    count=sdata.length;
    var tre;
    var td;
    for (var i=0;i<count;++i) {
        tre=document.getElementById('tr'+i); 
        td=tre.getElementsByTagName('td').item(1);
        if (td.getElementsByTagName('a').length<=0) {//如果下载链接不存在，则添加链接
            td.innerHTML='<a href="'+Base64.decode(sdata[i]['url'])+'" title="下载 '+decodeURIComponent(sdata[i]['title'])+'"><img src="http://t.douban.com/pics/download.gif" class="down_mp3"/></a';
        }
    }
}
downDouMusic();
